Include timestamp in nanobench JSON file name

infra/bots/recipes/swarm_perf.expected/big_issue_number.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
       "[SLAVE_BUILD]\\skia\\infra\\bots\\assets\\skp\\VERSION",
       "/path/to/tmp/"
     ],
     "name": "Get downloaded SKP VERSION"
@@ skipping 140 matching lines @@
       "~inc1.ico",
       "~inc0.png",
       "~inc1.png",
       "~inc2.png",
       "~inc12.png",
       "~inc13.png",
       "~inc14.png",
       "~inc0.webp",
       "~inc1.webp",
       "--outResultsFile",
-      "[CUSTOM_[SWARM_OUT_DIR]]\\perfdata\\Perf-Win8-MSVC-ShuttleB-GPU-HD4600-x86_64-Release-Trybot\\data\\nanobench_abc123.json",
+      "[CUSTOM_[SWARM_OUT_DIR]]\\perfdata\\Perf-Win8-MSVC-ShuttleB-GPU-HD4600-x86_64-Release-Trybot\\data\\nanobench_abc123_1337018001.json",
       "--properties",
       "gitHash",
       "abc123",
       "build_number",
       "5",
       "issue",
       "2147533002",
       "patchset",
       "1",
       "patch_storage",
@@ skipping 40 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@  os.makedirs(path, mode)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]